GGG ITS8 Diode Switching Problem

[64fx]

I just finished up my ITS8 kit with the "Very Expensive Boutique Mods" from GGG.  I did the asymmetrical diode clipping on one side using the germanium diodes included in the kit and the included red LED's on the other side.  With the switch in the middle position (diode lift) I don't hear much difference than from the germanium diode side of the switch (the only way I can really hear a difference is to close my eyes and pretend I hear it...haha...).  Anyway, my biggest issue is when I switch to the red LED side, the volume drops tremendously.  I would guess it's probably a 20db drop.

Any idea what's going on?

Thanks!
Daniel

[64fx]

Here's a little more info.  I think I was partially mistaken.  In my last post I stated there was very little difference between the center and germanium sides, which was totally wrong.  Here's the new scenario.  The huge volume difference only seems to be noticeable when the drive pot is turned up.  With the drive at "0" I can switch between all 3 positions, and there is very little difference in volume.  However, when I turn up the drive pot the LED side and center position seem to stay the same and the germanium diode side gets extremely loud.  Should this be the case?  If so, can I put some sort of resistor inline to tame it down some?  (For what it's worth, I measured voltage going out from each set of diodes and the off position, and they all showed up around 4.3v if that means anything.  That was the only way I knew how to see if they were acting the same.)

Thanks in advance for your help!
Daniel

[ianmgull]

Sounds to me like it's doing what it's supposed to, but I think you're looking at your switch backwards...

The quiet set of diodes is most likely the germanium set. Most GE diodes clip around .3v so you're going to have a volume drop with those. On the other hand, the LED's have a foward voltage probably of at least 1.5v (depending on what you're using) so they aren't going to clip that much of your signal at all. The middle position is opamp distiortion.

[ampgeek]

Hey Daniel,
I have built four GGG ITS-8 w/expensive boutique mods/ asym. clip and have observed the same significant drop in volume on the germanium side in every one.  I thought that the first couple of times it was a bum diode(s) but after the others I came to the conclusion that it was normal.  So much for the germanium mystique...at least to my tin ears!

BTW: I have taken to using socket pins in all of the places that I think I will want to experiment with different value/types of components (e.g., different types of diodes in this case).  A couple of swift cuts with a sharp utility knife to liberate them from their plastic bodies and...plug and play nirvana!  They even accept the wires used in the GGG kits.

Cheers,
Dave O.

[64fx]

Thanks for the info.  I'm glad to know it's not just me.  A friend of mine played with the one I built the other day and actually likes the germaniums the best.  I personally like the louder ones! Haha!

Ampgeek, have you tried swapping out the IC's with the extra ones that come with the kit?  I was so glad to get mine together that I didn't want to take it apart to try them out.  Also, have you compared the silicon diodes to the germaniums?

Thanks again,
Daniel

[64fx]

Sorry Dave for calling you "ampgeek" ...I looked over your name in your post....

[ampgeek]

Daniel,
No worries at all my friend.  I have been called a whole hell of a lot worse before!! 

I did swap out the IC's and there are slight differences between them all.  I also slipped in a TLC2272ACP for giggles as well.  I ended up keeping in the JRC4558 and running it at 12V.  That seemed to work the best with my rig.

So...they all sounded good to my ear with none being significantly better than any other.  BTW: My main guitar is a '72 LP Deluxe and my two primary amps are both homegrown mutations.  One is a Dumble'esqe clone and the other is an all octal Fender Bassman (5F6A) in a 2 X 12" curly maple cabinet.  I play primarily classic rock with a bit of blues and jazz to keep things fresh and different.

I say go ahead and have a go at them as your set-up may identify a sweet-spot with a particular IC.  A quick suggestion: I use a loose Exacto knife blade as a straight edge along one row of IC legs to get them to line up in the sockets.  Can't remember where I heard that one..but...THAT makes swapping them out a breeze.

With all else being equal, I found the silicon diodes to be much louder than the germaniums but not quite as loud as the stock LED's.  Also, slightly more "fuzzy" than both.  Mine spends the vast majority of it's time on the LED setting.  However, I built one for the other guitarist in my band and he swears by the silicon setting.  And...I couldn't argue as he sounds great.  Showing...once again...to each his own on that quest for tonal nirvana!!

Cheers,
Dave O.